Piezoelectric resonator device of tuning fork type

Abstract

Disclosed is a piezoelectric resonator device. This piezoelectric resonator device comprises a piezoelectric substrate having an almost rectangular plane shape. The piezoelectric substrate is provided with a slit extending to the inside from one edge of the piezoelectric substrate, for forming a tuning fork portion, and a pair of slits for separating the tuning fork portion, spaced apart from the slit forming the tuning fork portion by a predetermined distance on both sides of the slit forming the tuning fork portion, and approximately parallel with the slit forming the tuning fork portion. Vibrating electrodes are formed on both major surfaces of the piezoelectric substrate at a piezoelectric vibrating portion, between the slits separating the tuning fork portion from non-vibrating portions of the substrate.

What is claimed is: 
     
       1. A piezoelectric filter with a tuning-fork-type vibrating portion, comprising: a piezoelectric substrate having a nearly rectangular plane shape having edges and opposed major surfaces, said piezoelectric substrate comprising a first slit defining inner edges of a pair of arm portions of a tuning fork portion, extending inward from one edge of said piezoelectric substrate, and a pair of second slits defining outer edges of said arm portions of said tuning fork portion extending inwardly from said one edge and provided approximately parallel with the first slit, said second slits being respectively on two opposite sides of the first slit, and   wherein: a first vibrating electrode and a second vibrating electrode are disposed on respective sides of the first slit with the first slit being interposed therebetween, localized at an innermost portion of the first slit on one of said opposed major surfaces of the piezoelectric substrate and spaced away from both said one edge of said substrate and said outer edges of said arm portions, and   a third vibrating electrode opposed to said first and second electrodes through the piezoelectric substrate disposed on the other of said opposed major surfaces of said piezoelectric substrate.     
     
     
       2. A piezoelectric filter with a tuning-fork-type vibrating portion, comprising: a piezoelectric substrate having a nearly rectangular plane shape having edges and opposed major surfaces, said piezoelectric substrate comprising a first slit defining inner edges of a pair of arm portions of a tuning fork portion, extending inward from one edge of said piezoelectric substrate, and a pair of second slits defining outer edges of said arm portions of said tuning fork portion extending inwardly from said one edge and provided approximately parallel with the first slit, said second slits being respectively on two opposite sides of the first slit, and   wherein: a first vibrating electrode and a second vibrating electrode are disposed on respective sides of the first slit with the first slit being interposed therebetween, localized at an innermost portion of the first slit on one of said opposed major surfaces of said piezoelectric substrate and spaced away from both said one edge of said substrate and said outer edges of said arm portions,   a third vibrating electrode opposed to said first electrode through the piezoelectric substrate disposed on the other of said opposed major surfaces of said piezoelectric substrate and electrically connected to said second electrode, and   a fourth electrode opposed to said second electrode through the piezoelectric substrate disposed on the other of said opposed major surfaces of said piezoelectric substrate.     
     
     
       3. A piezoelectric filter with a tuning-fork-type vibrating portion, comprising: a piezoelectric substrate having a nearly rectangular plane shape having edges and opposed major surfaces, said piezoelectric substrate comprising a first slit defining inner edges of a pair of arm portions of a tuning fork portion, extending inward from one edge of said piezoelectric substrate, and a pair of second slits defining outer edges of said arm portions of said tuning fork portion extending inwardly from said one edge and provided approximately parallel with the first slit, said second slits being respectively on two opposite sides of the first slit, and   wherein: a first vibrating electrode and a second vibrating electrode are disposed on respective sides of the first slit with the first slit being interposed therebetween, localized at an innermost portion of the first slit on one of said opposed major surfaces of the piezoelectric substrate and spaced away from both said one edge of said substrate and said outer edges of said arm portions, and   at least one back electrode opposed to said first and second electrodes through the piezoelectric substrate disposed on the other of said opposed major surfaces of said piezoelectric substrate.